The present invention relates to a rotary transmission mechanism for use with an air/hydraulic chuck or cylinder which eliminates friction loss, greatly increases transmission efficiency, and minimizes installation space.
A bearing is commonly used to support a rotary member to a fixed member so that the rotary member can be rotated concentrically on the fixed member without causing much transmission loss. However, the revolving speed of the rotary member must be maintained within a limited range to prevent the occurrence of overheat, which may cause the rotary member to deform.
FIG. 1 illustrates a rotary transmission mechanism for use with an air/hydraulic cylinder which comprises two thinner bearings 130 to support a cylindrical rotary member 14, and an idle shaft 15 inserted in the cylindrical rotary transmission device 14. As a flow of compressed air (hydraulic fluid) P is continuously compressed into inlet connectors 16, 17, it immediately flows through passage ways 18, 19 to force a cylinder in holding down a chuck or releasing it. At the same time, part of the compressed air fills up the gap 157 between the cylindrical rotary member 14 and the idle shaft 15 to reduce the friction between the bearings 130 and the rotary member 14. This mechanism requires high precision, i.e., the roundness of the rotary member 14 and the idle shaft 15 and the concentricity therebetween are critical (tolerance below 0.005 mm is demanded), and the materials to be used should be of low coefficient of thermal expansion. Therefore, this structure of rotary transmission mechanism is expensive to manufacture, and the manufacturing cost of this structure of rotary transmission mechanism is directly proportional to its capacity. Because bearings are used, the revolving speed of the mechanism is limited. Further, before shifting the idle shaft 14 forwards or backwards, the rotary motion of the idle shaft 14 must be stopped by a brake or like means. Stopping the rotary motion of the 20 idle shaft 14 during the operation of the rotary transmission mechanism consumes additional power and causes a friction loss.